6. Female subjects of childbearing potential and male subjects with female partners of childbearing potential must be willing to avoid pregnancy by using an adequate method of contraception for 2 weeks prior to screening, during and four weeks after the last dose of trial medication. Adequate contraception is defined as two barrier methods, or one barrier method with a spermicide, or intrauterine device. The use of hormonal contraceptives should be avoided in female subjects of childbearing potential due to a possible drug-drug interaction.